Unit test configuration

Every now and then your unit tests depend on external services
- be it a database or LDAP server or a company's web service.
Access to those services and servers require creditentials, be it
username and password combinations or API keys.

Such confidential information may often not be distributed, and
your unit tests should not have them coded into.
Instead a separate config file template,
config.php.dist, should be shipped.
To run the tests, the user creates a copy of that configuration
template, saves it as config.php and adjusts it.